1. Field of the Invention
The present invention relates to a power transmitting device, a power feeding system, and a power feeding method.
2. Description of the Related Art
In recent years, electronic devices using power as a prime mover, as typified by mobile devices such as mobile phones or notebook personal computers, are often used while being carried. Also, transportation means such as bicycles and automobiles using electric power as a prime mover have been developed from the point of view of environmental cleanness and safety.
Since such portable electronic devices and such transportation means are often used outdoors, it is difficult to constantly supply power from a commercial power supply distributed to each house, through wires. Therefore, the portable electronic devices and the transportation means are provided with batteries which are charged from a commercial power supply in advance and operate by power supply from the batteries.
However, since the amount of power stored in the batteries is finite, users need to recharge the batteries outdoors in order to continue to use the portable electronic devices or the transportation means in the case where power stored in the batteries is exhausted when they are in use outdoors. Accordingly, power feeding service which can be used outdoors has been required in addition to conventional power feeding service with which power is distributed to an indoor commercial power supply.
A power feeding method and a power feeding system having high versatility with which an unspecified number of users can use them and having high supply efficiency with which the amount of supplied power and the speed of power supply become high, which are different from the conventional power feeding service used indoors by certain individuals, are needed for power feeding service given outdoors.
Therefore, a wireless power feeding method in which power feeding is performed wirelessly has been researched in addition to a conventional wired power feeding method using a wire. As the wireless power feeding method, for example, an electromagnetic coupling method (also referred to as an electromagnetic induction method), an electric wave method (also referred to as a microwave method), and a resonance method (also referred to as a resonant method) have been proposed, and there is a report for a further improvement in efficiency of power transmission (power transmission efficiency) (e.g., see Patent Document 1).